Pump



Sept. 1, 1942. A. G. scHLossER -2,294,609

PUMP

Filed Oct. 2l, 1940 Y. 45 Mil?! M25/5% 27 Arf/wr c. .sch/068er ms xronnsv Patented Sept. 1, 1942 PUMP Arthurv G. Schlosser, Detroit, Mich., assignor to Candler-Hill Corporation, a corporation of Michigan Application October 21, 1940, Serial No. 362,051

12 Claims. (Cl. 10S-42) the inlet port of the pump, as from an auxiliary My invention pertains to pumps, and more particularly to airplane fuel pumps of the type having automatic release and by-pass valve means for regulating the delivery pressure of the fuel supplied to the carburetor and for permitting the by-pass of fuel through the pump from an auxiliary or manual pump.

It is an object of my invention to provide a constant pressure fuel pump ofimproved compact construction having improved operating characteristics especially suitable for use on aircraft for delivering fuel to the carburetor at a uniform and constant pressure with greatly varying speeds of rotation and rates of fuel consumption and also of such construction that the discharge pressure is not affected either by a varying suction or pressure applied to the fuel at the intake of the fuel pump of such magnitude as may be caused by the maneuvering of an airplane.

It is also an object of my invention to provide a fuel pump having constant pressure delivery characteristics comprising a pump having in combination release valve means which is pressure balanced so that neither inlet pressure nor outlet pressures directly contacting the Valve means have any substantial effect tending to open or close the valve means, and a fuel pressure responsive actuator connected therewith and the actuator being mounted in the pump assembly to be exposed only to the outlet pressure so that the pressure of the de liveredfuel is automatically regulated and is not influenced by the variations of pressure in the inlet port las caused by the maneuvering of the aircraft.

It is a further object of my invention to provide an improved fuel release and by-pass valve assembly for such pumps.

It is also an 'object of my invention to provide a fuel pump having a compact double valve arrangement for releasing fuel from the outlet to the intake side of the pump through two spaced valve seat apertures, while also alternatively operably as a by-pass valve for by-passing fuel through the pump when applied under pressure in the intake port from an auxiliary pump.

Another object of my invention is to provide in such a fuel pump wherein the fuel release and bypass valve assembly comprises two valves arranged to seat upon two spaced valve seat apertures, an actuator responsive only to the pressure of the pumped or discharged fuel and so connected to the valves that both are opened as a unit in response to increasing discharge pressure, and

means permitting separate operation for by-passing in response to fuel applied under pressure in 55 or manual pump.

vAnother objectl of my invention 'is to provide such a fuel pump, double relief valve and bypass assembly, wherein one of the valves is provided with an extending hub portion having an aperture therein, a stationary guide pin extendsl from the housing into the hub to act as a guide and also as a dashpot to damp out vibrations of the valve, the other valve is slidably disposed on the hub portion of the rst valve and has a portion engageable therewith for simultaneous operation and the valves are seated upon spaced valve seat apertures in a passageway connecting between the inlet port and the outlet port of the pump in such a manner that the first mentioned valve opens against inlet pressure and the other valve opens against outlet pressure, spring means urging the valves to seated positions so that the second mentioned valve may bev lifted by the uid pressure to by-pass fuel from inlet to outlet when the inlet pressure is increased and outlet pressure decreases, and pressure responsive actuator means is provided exposed t-o the outlet pressure and connected to the first mentioned valve so that both valves are opened as a unit to release and discharge fluid from the outlet back to the inlet when the outlet pressure exceeds a predetermined value. j t

A further object of my invention is to provide an improved arrangement for attaching a nonmetallic diaphragm in unpierced condition to a valve to be controlled thereby.

Further objects and advantages are within the scope of my invention, such as relate to the arrangement, operation and function of the related elements ofthe structure, to various details of construction and to .combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification in commotion with the drawing disclosing specie embodiments of my invention, in which:

Fig. 1 is an end elevational view of my improved fuel pump;

Fig. 2 is a longitudinal sectional view taken'on line 2 2 of Fig. 1;

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig". 2;

Fig. 4 is an enlarged partially diagrammatic view illustrating the operation of the valves; and

Fig. 5 is an enlarged fragmentary sectional view showing a modification of the valve seat construction.

Referring more particularly to Figs. 1, 2 and 3 of the drawing, I have illustratively disclosed an improved rotary type of fuel pump of a well known construction, although it is to be understood that my improved relief valve and by-pass arrangement may also be advantageously utilized in combination with other typesof fuel pumps. As shown, the housing or casingl consists of a lower or pump housing 3 and an upper or valve housing 5 mounted and secured thereon as by bolts 6 passing down through the valve housing into the pump housing. The casings may be made in any suitable manner, and are preferably castings which have been lcored to provide fluid conducting passages therein. -The pump housing is provided with an inlet port opening 1 into one side and an outlet port opening 9 from the other side and these are internally threaded for convenient connection respectively with a fuel tank and carburetor in any system wherein the fuel pump is to be installed. From the inlet port 1 in the pump housing a passage II leads upwardly and connects with a passage I3 in the valve housing which is aligned therewith. The inlet pressure passage I3 in the valve housing opens in opposite directions through two spaced valve seat apertures I5 and I1 into an outlet pressure passage I9, which is suitably cored out of the valve housing 5 in surrounding relation. From the outlet port 9 in the pumphousing a passage 2| vleads up and connects with the outlet passage I9 in the valve housing, so the passages II, I3, I9, and 2| connecting in conductive relation form a passageway through the housing of the unit, for by-passing uid through the unit from the inlet 1 to the outlet 9 in shunt with the pump, `or for releasing pumped uid from the outlet back the inlet.

Referring to Fig. 2, it will be seen that the pump housing 3 is provided with a pump aperture orl bore 23 extending therethrough and having al n liner 3| and an outer bearing ring 33 and these` elements are secured in assembled relation therein by a.r cover 35 clamped rmly on the end of the pump housing as by bolts 31 passing thereinto. The liner 3| is provided with a bore 39 which is eccentric to its outer diameter and which bore has a diameter larger than the inside diameter of the bearing rings. The outer diameters of the liner and of the bearing rings are equal and when assembled in the pump housing are held in proper alignment. A rotor 40 of cylindrical conformation is disposed between the rings 29 and'33 and within the liner and has end portions of reduced diameter journalled to rotate in the bearing-rings. The intermediate portion of the rotor 40 is of larger diameter running closely against the upper side of the eccentric bore 39 in the liner 3I`. The intermediate portion of the rotor is provided with slots 4| cut radially therethrough for slidably guiding vanes 43, as shown in Fig. 3, the inner ends of which engage a vane spacer pin 45 which oats freely in an axial bore of larger diameter extending through the rotor. The outer ends and the inner ends of the vanes 43 are rounded or curved and the diameter of the vane spacer pin 45 is suitably selected with reference to the lengths of the vanes so that the outer ends of the vanes run snugly against the inner surface of the bore 39 in the liner which, being eccentric relative to the axis of rotation of the rotor, causes the vanes to be extended from the rotor when in the lower portions of their circuit of rotation and to be retracted when rotated to the upper positions. With the rotor rotating counterclockwise, as seen in Fig. 3, the extended vanes carry the fluid through under the rotor in the direction represented by the arrows and the pumped fluid cannot return above the rotor because the vanes are there retracted and the rotor is running closely against the liner. 'I'he liner 3| is provided with cut away portions 41 and 49 adjacent the inlet and outlet ports of the pump for passing fluid to and from the rotor. To assure that the liner 3| is assembled'and retained in a proper position in the pump housing, it is provided with a slot 5I in the upper side which receives the end of a pin 53, extending down from the housing 3.

Driving connection is extended from the right hand end of the rotor which has an aperture 54 of square or other non-circular shape for receiving one end of a drive shaft 55 which is similarly shaped. The other end of the drive shaft 55 extends from the pump housing to be meshed with and driven. by any suitable driver on an engine on which the pumpi is mounted. A shaft seal is provided comprising a stationary seal ring 51 which is seated upon a gasket 59 in the annular socket 21 in the end of the pump housing, where it isA firmly clamped by an annular rear plate 6I secured tothe housing as by bolts 63 of which a plurality are provided at circumferentially spaced points around the annular plate. Running in snug tting relation against the stationary seal ring 51 is a spring pressed sealing l ring 65 having prongs 61 passed through slots in a shaft ring 69. A spring 1| reacts between the end of the rotor and the shaft ring 99 for continuously pressing the rotating shaft seal ring 55 against the stationary seal ring 51. The shaft 55 is' also provided with a seal ring or gasket 13 of -rubber of other similar material of a suitable diameter to be pressed snugly on the shaft and to press snugly against both the shaft and the adjacent side of the rotatable sealing ring 55. This rubber ring gasket 13 serves to restrict the leakage of fluid and allows slight misalignment of the drive shaft 55.

As a further precautionfan annular leakage collecting groove 15 is formed in the surface of the annular rear plate 6I for receiving any fluid which might leak past the seal. A plurality of drain holes 11 are provided connecting from the collecting groove in various directions and these are internally threaded and closed by plugs 19, as may be seen in Fig. 1. When the pump is installed, the plug in the lowest position is removed,

and a pipe line is screwed therein for draining away any leakage for safe disposal.

In accordance with my invention I provide an improved double release valve arrangement for automatically regulating the pressure of the fuel delivered by the pump and the same means also being operative to by-pass fuel through the housing around the pump when fuel is applied in the inlet port of the pump under pressure, as from a manual or other auxiliary pump. For this purpose the passage I3 in the valve housing, as may be seen in Figs. 3 and 4, connects through the two valve seat apertures I5 and I1 opening in opposite directions-into the outlet connected passage I9. 'I'he two valve seat apertures I5 and I1 are spaced apart in aligned relation. To restrict the ow of fluid through the lower aperture I1 a lower or inner valve 8| is provided of a suitable size for seating thereon. When the inner valve 8l is opened itis lifted from its seatagainst the inlet port pressure from the passage I3. For assembling the lower valve 8| the upper 'valve seat aperture is made just slightly larger so that the valve can be passed therethrough. A hub portion 83 projects up from the upper side of the inner valve 8| extending upwardly toward or through the V,upper valve seat aperture I5. The hub 83 is provided with an axial aperture 85 for slidably receiving the upper end of a guide pin |11 which is secured stationarily at the lower end in a suitable aperture in the lower portion of the valve housing 5 and disposed in concentric alignmentwith the valve seat apertures. In this manner the inner valve 8| is guided in moving toward or away from the valve seat I1, and the diameter of the guide pin 91 is suitably selected relative to the diameter of the aperture 85 in the hub 93 so that it also serves as a dashpot to suitably damp out vibrations of the valve. A guide sleeve 89 may also be provided extending from the valve 8| down-around the guide stem 81 to additionally resist any tendency of the valve to turn over.

An upper or outer valve 9| is provided for seating upon the upper valve seat aperture |5 to restrict the flow of fluid therethrough. The outer valve 9| is centrally apertured to slide freely upon the hub 83 of the inner valve for guiding said outer valve in its movements toward and away from its valve seat I5. Projecting downwardly from the outer valve 9| is an abutting portion or sleeve 93 for engaging the inner valve 8| so that both valves may be operated simultaneously as a unit under certain conditions to be described subsequently. The depending sleeve 93 also serves to accurately guide the movements of the outer valve. Because outlet pressure tends to close one valve and open the other, these two forces cancel out on the valve assembly as a unit but it does tend to maintain the two valves abutted together to act as a unit.

For controlling the operation of the valves I provide a pressure deformable diaphragm 95 which is preferably of circular conformation.. The outer periphery of the diaphragm 95 is seated in an -annular groove 91 in the upper end of the valve housing 5 where it is snugly clamped and sealed by the valve cover 99 which is secured thereon by bolts 6 passing into the valve housing. Although any suitable flexible material may be used for making 4a suitable diaphragm, I preferably utilize a non-metallic material such as rubber, synthetic rubber, or some rubber like material. For securing the central vportion of the diaphragm to the valve I provide interfitting portions on these two elements so that they may be buttoned or snapped together Without the necessity for piercing the diaphragm.

As shown in- Figs. 3 and 4, one arrangement forl accomplishing this is to provide the upper end of the valve hub 83 with a socket |02 and to provide connecting means comprising a hollow protuberance |03 on the diaphragm of a size suitable for fitting snugly thereinto. The aperture in the hub of the valve being thus formed buttoned or snapped together without the necesall .the way through facilitates grinding a smooth A bore in the hub. Interlocking parts may be provided as by providing an annular groove |05 on the side walls of the socket for receiving laterally v form to provide mterntting parts which may be sity of perforating the diaphragm. Additional means may be provided for locking the intertting parts together such as a plug |99 lwedged into the hollow protuberance, as shown. In this construction the under side of the diaphragm is exposed to the pressure of the pumped fluid discharged from the pump into the outlet port 9 of the pump.

The valve cover 99 is provided with an aperture passing axially up through the upper end wherein is seated a manual pressure adjusting screw |I3, having a lateral flange ||5 resting thereon land a knurled knob ||1 to provide for convenient adjustment. 'Ihe threaded adjusting screw ||3 projects down into the upper end of the aperture in the cover and it carries a follower II9 having a flange |2| pressing on the upper end of a compression spring |23 the lower end of which reacts upon the upper end of the plug |09 which may be inserted into the pro-` tuberance in the diaphragm. The plug |09 also serves as a wedge for more rmly attaching the diaphragm to the valve. To prevent the follower ||9 rotating with the adjusting screw |l3, the flange |2| on the follower Vand the cross-section of the aperture are made of any non-cir-l locknut is then tightened which holds the ad- .'lustment permanently and also clamps the ange ||5 of the adjusting screw down to make a uid tight seal on the valve cover.

To seat the upper or outer v alve 9| lwhich is y slidable upon the hub of the inner valve, I provide a second or auxiliary light weight spring |21 -which is' concentrically disposed thereon where it reacts between the outer valve and the diaphragm. If desired, the upper end of the spring |21 may press against the diaphragm or a member |29 projecting from the upper end of the hub ofthe inner valve. The auxiliary spring |21 acts in series with the main spring |23 for seating the outer valve 9| and normally the outlet pressure applied thereon also aids in seating this valve. The auxiliary spring |21 is selected of suitable strength so that when. outlet pressure decreases and fuel under pressure is applied in the inlet port of the pump, as from a hand pump, this valve will be lifted to by-pass fuel through the housing and out of the outlet port to thev plug |33 which is apertured to the atmosphere.

When used in an installation in conjunction with a super-charger the super-charger pressure is applied on the .carburetor and backs up through the fuel line to the underside of the diaphragm. When used in such, a system, a lconnection may be conveniently made through tle vent for applying the super-charger pressure therethrough to the upper side of the vdiaphragm 95 to compensate for the super-charger pressure which is applied on the carburetor.

To provide uid tight vsealed joints, any suitable yielding gask t or packing material is inserted between the various parts as these are assembled outlet port to the inlet port.

by-pass assembly, it has been necessary to asf sume a definite direction of rotation of the pump which has been taken as counter-clockwise, indicated by the arrow, as viewed in Fig. 3. yOperat- Iing in this direction of rotation the port 'I at the left hand side is the inlet port and the port 9 at the right hand side is the outlet port as indicated by the arrows representing the direction of fluid flow. d

However, the internal combustion engines used on aircraft do not all require the same pump rotation. My improved fuel pumpalso has the important advantage that it is reversible and 'may be operated equally well in either direction. W'hen operating in the reverse direction from that assumed, the fuel is pumped in the reverse direction, the inlet becomes the outlet and vice versa. For such an installation the normal functioning Vof the pressure regulating relief and bypass valves is maintained merely by the simple expedient of mounting the valve housing 5 on the pump housingl 3 in a. reversed position so that the inlet passage |3 therein is connected with the port in the right hand end of the pump housing and the outlet passage I9 in the valve housing is connected with the port in the left hand end of the pump housing, as viewed in Fig. 3.

Operation of the pump is attained by mounting the pump on the engine of the aircraft with the end of the drive shaft 55 in mesh with a driver on the engine where it is secured in position by bolts passing through the holes |35 in the mounting flange |31, shown in Fig. l. Assuming that rotation is in a counter-clockwise direction, as viewed in Figs. 3 and 4, fuel is drawn into the left hand or inlet port of the pump housing 3 and it is discharged from the outlet port 9 at the right hand end, as indicated by the arrows. It will be understood that in such an installation the inlet port l of the pump is connected by a suitable pipe line with the fuel reservoir and the outlet port 9 is connected to the carburetor of the engine.

As the pump operates, the volumebf fuel delivered into the outlet port by the pump varies greatly with the speed of the pump and the engine which drives it. As the demand for fuel varies with the load on the engine and also because the capacity of the pump greatly exceeds the fuel requirements of the engine, a-back pressure is built up in the discharge port 9. As previously described, the under side of the ilexible diaphragm 95 is exposed to the pressure in the outlet port 9 and, as soon as the force applied thereon is greater than or over balances the main valve spring |23, the two valves 8| and 9| of the pressure balanced valve assembly are lifted.

In Fig. 3, both valves 8l and 9| are shown in closed positions which condition could only prevail for an instant as the engine is starting up or if a condition is assumed where the demand for fuel is equal to the full delivery capacity of the pump. During normal operation the two.`

valves of the pressure balanced release valve assembly are opened more or'less, as shown by dotted lines, depending upon the speed and load conditions, so Jthat the unused portion of the pumped fuel is being released back from the The carburetor then receives an ample supply of fuel at a predetermined regulated pressure in accordance with the setting of the adjusting knob.

, It will be seen that because there are two oppositely directed valve seat apertures, the release valve means is substantially pressure balanced, has large capacity in a small compact space, and being responsive only to outlet pressure which acts on the diaphragm a very accurate pressure regulation is obtained irrespective of variation of suction and pressure in the inlet port as caused by maneuvering of the aircraft, or other vehicle on which it may be installed. The two desirable to be able to by-pass fuel to the car-r buretor from some manual or other auxiliaryl pump. This purpose is also effectively accomplished by the valve arrangement provided. When fuel under pressure is applied in the inlet port i of the pump, the upper or outer valve 9| is lifted and fuel flows therethrough, as shown in Fig. 4, and the manually pumped fuel is readily delivered to the carburetor without the necessity of providing a special by-passing line, or even the trouble of operating a `try-pass valve manually, as the operation of the by-pass in the pump takes place automatically without any special attention from the operator.

In Fig.'5, I have shown 'a modified arrangement of the valve seat construction comprising Va valve seat ring insert |39 which is disposed in the upper valve seat aperture I5. The valve seat insert |39 may be a snug t pressed into the upper valve seat aperture, and it is installed after the lower or inner valve 8| has been installed. This arrangement has the advantage that the two valves 8| and 9| may be made exactly the same size and the valve assembly will be exactly pressure balanced in its operation. Also it is possible by this arrangement to make the inner or lower valve 8| larger than the outer valve 9| so that the pump will have a falling pressure delivery characteristic with increasing suction (decreasing absolute pressure) in the inlet port, if that is desired. In the 4'first embodiment, previously described, the upper valve seat aperture I5 must be slightly larger than the lower or inner valve 8| which must be passed therethrough in assembly. 'I'his causes a slight rising pressure delivery characteristic with increasing suction in the fuel inlet port. However, the difference necessary in the sizes of the inner and the outer valves 8| and .9| is only slight, even when a ring insert is not provided in vthe upper valve seat aperture, and such expressions as "pressure balanced as used throughout are intended to apply to either such arrangement of these valve seat apertures and valves. The improved release and by-pass assembly has been shown in combination with one type of rotary pump but it is to be understood that this arrangement may be advantageously utilized with various other types of pumps.

Itis apparent that within the scope of the invention modifications and different arrangements may be made other than herein disclosed, and the present disclosure is illustrative merely, the invention comprehending variations thereof.

I claim:

1.'In an fuel pump the combination of, a casing having a fuel inlet port and a fuel outlet port, a pump within said casing for effecting a transfervof fluid through the casing from the inlet port to the outlet port, said casing being provided with passage openings-through which uid may be transferred between said ports in shunt with said pumping means, pressure balanced valve means in said passage for restricting the flow of fluid therethrough and said valve means being balanced for variations of pressures in both the inlet port and the outlet port, discharge pressure responsive actuator means exposed to the discharge pressure in the outlet port from said pump, and means connecting said discharge pressure responsive actuator means to operate the valve means for returning pumped fluid from the outlet port to the inlet port to vregulate the pressure of the fluid delivered by the pump to a substantially constant value.

2. In a fuel pump the combination of, a casing having-'a fuel inlet port and a fuel outlet port, a pump within said casing for effecting a transfer of fluid through the casing from the inlet port from the inlet side to the outlet side, two valves for engaging said stationary valve seats n1 uid ow obstructing relation, one of said valves opening toward the inlet pressure and the other valve opposing the pressure of the pumped uid against the first mentioned spring for opening both of said valves to return a portion of the fuel to theV diaphragm exposed to the discharge pressure in the outlet port of said pump, and means securing the central portion of the discharge pressure reopening toward the outlet port pressure, a pressure responsive actuator exposed to the discharge pressure in the outlet port from said pump, and means connecting said actuator to open said valves as a unit so that both valves open in response to a pressure greater than a predetermined pressure in the outlet port opening both valve seat apertures for returning a portion of g sponsive diaphragm to operate the pressure balanced valve means in accordance with fluid pressure in the outlet port of the pump for returning pumped fluid from the outlet port to the inlet port to regulate the pressure of the fluid delivered by the pump to a substantially constant value.

5. In a fuel pump the combination of, a casing having a fuel inlet port and a fuel outlet port, a pump within said casing for effecting a transfer of uid through the casing from the inlet port to the outlet port, said casing being provided with passage openings through which fluid may be transferred between said ports independently of the action of said pumping means, balanced pressure valve meansin said passageway for regulating the flow of fluid therethrough comprising two aligned stationary valve seat apertures spaced apart and opening in opposite directions from the inlet to ,the outlet of the pump, two valves for engaging said stationary valve seats in uid flow obstructing relation, one of said valves opening toward inlet pressure and the other valve opening toward outlet port pressure, spring means for urging said valves to seated positions, a flexible pressure deformable member exposed to the a passageway through which fluid may be transferred between said ports independently of the action of said pumping means, balanced pressure valve means in said passageway for regulating the fiow of uid therethrough comprising two valve seat apertures spaced apart in aligned relation and opening in opposite directions, from the inlet port to the outlet port of the housing, two valves for engaging said valve seats in fluid flow obstructing relation, one of said valves opening against inlet port pressure and the other valve' opening against outlet port pressure, guide means for slidably guiding said valves in relatively movl the discharge pressure of said pump and connected to said valves in a suitable manner for discharge pressure of the pump and connected to said valves for opposing the force derived from the pumped fuel against said spring means for opening. both of said valves to return a portion of the fuel to the inlet for regulating the pressure of the fuel delivered by the pump.

6; An aircraft fuel pump, relief valve and bypass assembly comprising the combination of, a

housing having fuel inlet and outlet ports, a pump in said housing for pumping fuel from the inlet port to the outlet port, said housing having a passageway through which fluid may be transferred between said ports independently of the action of the pump, said passageway including a passage extending into the housing from the outlet port and a passage extending into the housing from the inlet port and having two valve seat apertures opening in spacedv aligned relation therefrom intothe first mentioned passage, an inner valve adapted to seat upon one of said valve seat apertures and open- .ing toward inlet port pressure, an outer valve for uging said inner valve toward seated po'sition, said outer valve being lslidably disposed upon the hub portion of the inner valve and having an extending portion engaging the inner valve so that both valves are unseated as a unit when the inner valve is lifted, an auxiliary spring acting in series relation with the first mentioned spring to seat the outer valve so that said outer valve may be opened against said auxiliary spring by the pressure of fuel applied under pressure into the inlet port, as from a manual pump, for by-passing fuel through said housing at times when the pump is not operating, a pressure responsive actuator exposed to the discharge pressure in the outlet port and connected to said inner valve for lifting both valves to open positions for returning fuel to the inlet port to regulate the pressure of fuel delivered by the pump.

7. An aircraft fuel pump, relief valve and bypass assembly comprising the combination of,-a housing having fuel inlet, and outlet ports, a pump in said housing for pumping fuel from the inlet port to the outlet port, said housing having a passageway through which fluid may be transferred between said ports independently of the action of the pump, said passageway including two valve seat apertures opening in spaced aligned relation, an inner valve arranged to seat upon one of said valve seat apertures and opening toward inlet port pressure, an outer valve adapted to seat upon the other valve seat aperture and to open toward the outlet port pressure, a guide pin secured stationarily on said housing and projecting concentri'cally toward said valve seat apertures, said inner valve having a centrally disposed hub extending therefrom toward the other valve, an aperture in said hub for receiving the end of said guide pin to serve as a guide for the valve and also as a dash pot for minimizing vibrations imparted to the valve, a spring in said housing for urging said inner valve toward seated position, said outer valve being slidably disposed upon the hub portion of the inner valve and having an extending portion engaging the inner valve so that both valves are unseated as a unit when the inner valve is lifted, an auxiliary spring acting in series relation with the first mentioned spring to seat the outer valve so that said outer valve may be opened against said auxiliary spring by the pressure of fuel applied under pressure into the inlet port, as from a manual pump, for by-passing fuel through said housing at times when the pump is not operating and a pressure responsive actuator exposed to the discharge pressure in the outlet port and connected to said inner valve for lifting both valves to open positions for returning fuel to the inlet port to regulate the pressure of fuel delivered by the pump.

8. In an aircraft'fuel pump and relief valve assembly the combination of, a housing having fuel inlet and outletI ports, pumping means Within said housing for pumpingfuel from the linlet port to the outlet port, said housing having a passageway through which iiuid may be transthe valve and a spring foi urging the valve to seated position.

9. In an aircraft fuel pump, relief valve and by-pass assembly the combination of, a housing having fuel inlet and outlet ports, pumping means within said housing for pumping fuel from the inlet port to the outlet port, said housing having a passageway through which fluid may be transferred between said ports independently of the action of said pumping means, balanced pressurevalve means in said passageway for regulating the flow of fluid therethrough comprising two valve seat apertures, said valve seat apertures being stationary in the casing and spaced apart, two relatively movable valves engageable together and engaging said spaced valve seats in fluid flow obstructing relation, one of said valves opening against inlet pressure and the other valve opening against outlet discharge pressure, a pressure responsive actuator exposed to the discharge pressure in the outlet port from said pump, means connecting said actuator to the valve opening against inlet port pressure for moving it engaging the other valve for moving both valves as a unit to open both valve seat apertures in response to a pressure greater than a predetermined pressure in the outlet port for returning a portion of the pumped fluid to the inlet to regulate the pressure of the fuel delivered by the pump, spring means urging said valves respectively to seated positions on the spaced valve seats and suitably selected to -permit the valve which opens against outlet pressure to open when outlet pressure decreases and the inlet pressure increases.

10. An aircraft fuel pump, relief valve and bypass assembly comprising the combination of, a

.housing havin-g fuel inlet and outlet portsa` pump in said housing for pumping fuel from the inlet port to the outlet port, said housing having a passageway through which iiuid may be transferred between said ports independently of the action of the pump, said passageway including a passage extending into the housing from the outlet port and a passage extending into the housing from the inlet port and having 'two valve seat apertures opening in spaced aligned relation therefrom into the first mentioned passage, an

" inner valve adapted to seat upon one or said ferred between said ports independently of the phragm having interftting irregularities which pmay be buttoned together in interlocking relation for securing the -unpierced diaphragm to valve seat apertures and movable toward the inlet port pressure when opening, an outer valve adapted to seat upon the other seat aperture and movable toward outlet port pressures, a guide pin for slidably guiding the movements of said inner valve, said inner valve having a centrally disposed hub extending therefrom, a spring in said housing for urging said inner valve toward seated position, said outer valve being slidably disposed upon the hub portion of the inner valve and having an extending portion for engaging the inner valve so that both valves are unseated as a unit when the inner valve is lifted, an auxiliary spring acting in series relation with the first mentioned spring to seat said outer valve which may be unseated by the pressure of fuel applied under pressure into the inlet port, as from' a manual pump, for by-passing fuel through said housing at times when the pump is not operating, a pressure responsive actuator exposed to the discharge pressure in the outlet and connected to said inner valve for lifting both valves to open positions for returning fuel to the inlet port to regulate the pressure of fuel delivered by thepump. l

11. In an aircraft fuel pump the combination of, a casing having a fuel inlet port and a fuel outlet port, a pump disposed in said casing for transferring iiuid through the casing from the inlet port to the outlet port, said casing having a passageway through which ud may be transferred independently of the action of the pump, pressure balanced valve means in said passage- Way for regulating the flow of fluid therethrough, a ilexible-diapliragm mounted in said casing so that the pump discharge pressure from the outlet port is applied on one side of the diaphragm, said diaphragm being connected to said pressure balanced valve means for opening the valve means when the pump outlet pressure exceeds a maximum value, a cover for enclosing the opposite side of the diaphragm, a spring for applying a predetermined biasing force tending to close said valve means against the tendency of the outlet pressure to open the valve means, a

-vent in said cover for applying any desired pressure and so that when the pump is used in a super-charged installation the super-charger pressure on the pumped fuel may be compensattherein.

ed for by also applying it on said other side of the diaphragm.

12. In a fuel pump the combination of, a cas' ing having'a fuel inlet port and a fuel outlet port, a pump within the casing for moving uid through the casing from the inlet port to the outlet port, a passageway in said casing through which uid may be transferred between said ports in shunt relation around said pump, a valve in said passageway for regulating the iiow of fluid therethrough, said valve having a hub, an aperture extending axially through the hub of said valve, said aperture being of circular crosssectlon, means in one end of said aperture for guiding the movements ofthe valve, an annular,4

recess in the side wall of said aperture adjacent the other end. thereof, a exible diaphragm mounted in said casing for exposure to outlet port pressures, connecting means projecting from said diaphragm into said aperture, and means extending into said annular recess in said aperturev for securing said connecting means ARTHUR G. scmossna. 

